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Wednesday, January 2, 2013

Yogurt Bacteria Could One Day Prevent HIV

On a recent, crisp winter day at a Lincoln grocery store, shoppers
perused dozens of different kinds of yogurt: harvest peach, strawberry,
Greek, Greek strawberry … the list goes on and on. Yogurt’s a healthy
snack for numerous reasons; it’s high in calcium, protein, magnesium and
potassium, to name a few. And if a University of Nebraska-Lincoln
professor’s research goes the way he hopes, yogurt could one day also
keep you safe from HIV.

It’s part of the research being conducted by Dr. Shi-hua Xiang,
professor with the Virology Center at the University of
Nebraska-Lincoln. But to understand how novel his approach is – and the
potential it holds, if it proves successful – we need a bit of
background first.

There’s been lots of talk recently about how to achieve an “AIDS-free
generation.” Progress is being made; the global rate of new HIV
infections dropped 20 percent in the last decade, and nationally, the
rate of new HIV diagnoses has remained relatively stable for the last
five or six years, according to the U.S. Centers for Disease Control.

“Even in the high incidence areas, like in Sub-Saharan Africa, we see it dropping every year (by) one or two percent,” said Dr. Charles Wood, director of the Virology Center. “So it’s really hopeful.”
But the numbers aren’t all good: 2.5 million people were still
infected with HIV in 2011, and a Nebraskan is infected with HIV every
three days. Of course, the easiest solution would be a vaccine – but
experts like Dr. Susan Swindells, an HIV researcher at the University of Nebraska Medical Center, say that’s decades away, if it’s possible at all.

Swindells pointed to measles, a virus that’s basically been wiped out
through the proliferation of vaccinations. In that case, the vaccine is
based on the natural immunity that results from people whose bodies
defeated the virus; HIV, however, attacks the immune system itself, so
there’s no natural immunity to use as the building block for a vaccine.

Similarly, while a measles virus is the same in Omaha as in South
Africa as in Japan, HIV is a different story, Wood from the Virology
Center said. The virus mutates rapidly, and so even within specific
populations there can be numerous strains.

And Swindells said existing animal test subjects don’t work very well for testing HIV.
“A chimpanzee you can infect with HIV, but they don’t get AIDS, and
they don’t get sick,” she said. “There’s only so much you can test.”

Xiang with the Virology Center acknowledged the complications.

“HIV is very challenging to us, scientifically,” he said. Given the
difficulties of formulating a vaccine, he decided to try something
different.

That’s where that grocery store yogurt comes in. Among the nutrients
mentioned earlier in the story, it’s also a great source of lactobacillus,
or that “good bacteria” touted all over the packaging. That’s what
Xiang is focusing his research on: he’s testing a genetically modified
version of the bacteria that would essentially act as a decoy, tricking
the HIV virus into attacking. But instead of letting the virus then pass
into and infect the body, the bacteria trap it.

“So you can actually neutralize the HIV virus,” he explained.

The bacteria, which has a fairly short shelf-life, then naturally passes from the body, taking the HIV virus with it.

The modified lactobacillus could be introduced to the body in several
different ways, Xiang theorized – including, perhaps, a spoonful of
yogurt. The idea is that the modified bacteria would then replicate
themselves in the areas where their counterparts already exists – the
mouth, the vagina, the rectum – which are also the main points of entry
for the HIV virus.

Now, Xiang is still at the beginning; he hopes to have his animal
testing completed by the end of the year, and if the bacteria prove
successful, quickly move onto human clinical trials. Because Xiang’s
approach is so different, animal tests are more helpful.

Several big questions remain: will the bacteria actually colonize? If
so, how long will they last? Would you need to get a booster shot, so
to speak – and if so, how often?

“And of course, the question is, ‘How effective it is?’” Wood said.
“As you know, (with) HIV, only one single virus can initiate infection.
You have to be completely, 100 percent-blocking.”

In contrast to the search for a vaccine, Xiang’s research is part of
Swindell’s strategy of choice: end the epidemic by simply interrupting
the transmission through prevention and treatment.

Vaccine or no vaccine, HIV is technically a preventable disease,
Swindell said. Regular treatment for infected people drops the risk of
transmission to 3 percent, and those not infected can take a daily
preventative pill and practice safe sex. But she acknowledged that these
methods require constant attention and action and can be prohibitively
expensive; HIV treatment costs about $1,200 to $1,500 per month, and 40
percent of her patients are uninsured.

“It’s somewhat pie in the sky, because we can’t even get everyone in
this country on treatment, and you know, we need to do it in places that
are very much more challenging,” she said.

On top of that, the key to getting treated is knowing that you have
HIV in the first place. According to the Kaiser Health Foundation, only
40 percent of Americans nationwide have ever been tested for HIV as of
2010. In Nebraska, that number drops to 26 percent.

So for now, the main thing is to just get tested, Wood said – and get treated.

“With that, I think we can hopefully go into the so-called ‘AIDS-free
generation,’” he said. “Not necessarily because of a vaccine, (but)
because of the effectiveness of treatment as prevention strategy.”